SICP blew my mind the first time, but I think it's most useful when you already have some hands-on coding experience (as I did). It's why we don't start teaching math with set theory.
But I don't think I would have appreciated without my prior exposure to programming. That said, I've also watched some MIT 101 math classes and they also seem like courses better suited for people who know/appreciate the basic content (beyond typical high school math). So maybe MIT selects for kids smart enough to grasp it.